Hello, DiagrammeR

Concept

• DiagrammeR allows algorithmically-generated diagrams to be created from simplified text descriptions of relationships. Even though a GUI diagram editor can be a powerful tool for expressing relationships that are already in your head, sometimes you want the computer to show you relationships between various things that you are unfamiliar with.
• DiagrammeR supports two different syntaxes:
  • grViz for node/edge diagrams
    • Can be laid out directionally (e.g. left to right), or radially (like a bicycle wheel), or in clusters with many interconnections (clumps)
  • mermaid for flowcharts/sequence diagrams
• Not as comprehensive as igraph, but IMO simpler

grViz 1

grViz(
'digraph sample1 {
A -> B
}')

grViz 2

grViz(
'digraph sample2 {
Boss -> Me
Boss -> "Co-worker"
}')

grViz features

grViz(
'digraph sample1 {
rankdir="LR"
A [ shape = diamond ]
// Transparency (alpha) using #rrggbbaa last byte
E [ fillcolor = "#0000FF80"; style=filled ]
A -> B [ label = "start" ]
B -> { C D }
{ C D } -> E
}')

grViz “dot”

Default linear layout:

grViz “neato”

“Repelling” spacing between nodes: graph [layout = neato]

grViz “twopi”

Circular “ranks”: graph [layout = twopi]

Tabular Diagram Construction

• DiagrammeR has functions that can let you build graphs from tabular data with tidyverse pipes, and sanity check the graph (e.g. verify only one boss per employee), and do computations on “connected” node data (e.g. count nodes “dependent” on a specified node)

mermaid Sequence diagrams

Useful for showing interactions between things/people (from documentation).

DiagrammeR Tips

• Particularly useful when you don’t know what the graph will look like once it is drawn, or the information in the graph may change frequently
• Avoid spending too much time trying to force grViz to create your “vision” of a graph… learn from what it has to show you and move on to a different tool if you feel you really must tweak the layout